When Frank Drake penned his famous equation in 1961, he gave us a framework to estimate the number of detectable technological civilizations in our galaxy. Beginning with the number of potentially life-supporting planets orbiting stars, he added the term F sub l, “the fraction of suitable planets on which life appears.” Habitable planets or moons possessing liquid water at their surface are considered candidates to support life as we know it, but can these worlds support the spontaneous origin of life called for in the Drake equation?
The Genesis Lab's research effort and its first instrument, the Genesis Engine 1.0, focus on the two dozen factors underlying F sub l that define urable planets on which life can emerge (Deamer et al. 2022). The Lab began as a collaboration between the BIOTA and SETI Institutes, and its first experiment got underway in early April of this year (figure 2).
Researchers have proposed two primary environments as potential birthplaces for life. The first is the salty seawater of Earth's oceans, specifically at hydrothermal vents that provide a source of energy (figure 3 above, left). The second environment is volcanic islands with hydrothermal fields commonly called hot springs (right). These hot springs contain fresh water distilled from seawater that falls as rain and undergo wet-dry cycles, which can provide the energy necessary for the chemical reactions required for the origin of life.
Nucleic acids are essential to all life because they carry genetic information that guides protein synthesis. The scientists are addressing a fundamental question: Were nucleic acids invented by early life forms, or did they spontaneously assemble before life began?
The project seeks to understand how nucleotides, the building blocks of nucleic acids, can be linked together to form long polymers like RNA and DNA without using enzymes. The experiment simulates conditions of the early Earth in a chamber containing 24 vials in a rotating aluminium disk warmed to hot spring temperatures. Each vial holds a dilute solution of nucleotides, and the heated vials are exposed to multiple wetting and drying cycles as the disk rotates. After several two-hour cycles, analysis of the polymer products determines how well their properties match those of known nucleic acids.
Early research results from the Genesis Lab conducted by BIOTA’s Dr. Povilas Šimonis have already shown that the wetting and drying cycles can synthesize long strands of nucleic acids resembling DNA and RNA. These conditions would have been common in volcanic sites on the early Earth and Mars. The next question is how nucleic acids became incorporated into the first cell-sized compartments to form “protocells” with increasing complexity. The answer may lie in the same wet-dry cycles that enabled the synthesis of nucleic acids. If membrane-forming compounds like fatty acids are present during cycling, the polymers become trapped between dry membranous layers and then bud off into protocells during re-wetting. Figure 4 shows previous results with “rings and strings” of nucleic acids made visible by atomic force microscopy (left), A protocell compartment stained with a dye glows with fluorescence that reveals the presence of encapsulated nucleic acids (right).
In 1871, in a prescient letter to his friend Joseph Hooker, Charles Darwin speculated that life may have begun in a “warm little pond.” Although individual protocells are not alive, populations of protocells cycling in hydrothermal pools have the potential to undergo a form of pre-Darwinian evolution toward living microbial communities. Figure 5 shows how dry, wet, and moist phases in such ponds can subject protocells and their polymer cargos to synthesis, aggregation, budding and recycling phases. Each phase provides opportunities for a variety of selective processes that impact cohorts of protocells. The rare few that survive the stresses build the next evolutionary rung on the ladder to life.
The Genesis Lab's ultimate goal is to establish conditions under which a comprehensive set of properties can emerge that are required for life to begin on a young, urable world. Perhaps only a fraction of habitable worlds are, in fact, urable, which is an important consideration for Frank Drake’s equation and the entire SETI project. With adequate support and time, the Genesis Lab's next generation of engines could help us to better understand the origin of life on Earth four billion years ago and the potential for life to emerge in other places, including exoplanets. To quote BIOTA co-founder David Deamer:
“For life to become intelligent, it must first begin.”
- BIOTA Institute - www.biota.org
- Deamer, D., Cary, F., & Damer, B. (2022). Urability: A Property of Planetary Bodies That Can Support an Origin of Life. Astrobiology, 22(7), 889-900.
- SETI Talks - Urable Worlds: Where and How can Life Start in the Universe?